You probably have a Bx chipset board, which may work with a katmai 600. I would go to Dell's website and see if any upgrades are available, or call them direct. My folks have a Dell with the pentium III 500, and I've wanted to upgrade it by changing the mobo, but then you can't use some of the Dell standard software. With a sloket adapter and bios upgrade, you should be able to use any of the 100 megahurtz ppga p3 cpu's, which are cheaper than socket 1. If you don't need the dell software, I would get a pc kit from pricewatch, which includes the case, power supply, cpu and heatsink, and transfer your hardrive, video card, etc. over to the new case. Check pricewatch and select you cpu speed.